Cocoa butter
Cocoa butter is the fat pressed from cocoa beans. Solid and brittle at room temperature, it melts at around 34–36 °C — just below body temperature, which is why chocolate melts in the mouth.
Its defining characteristic is polymorphism: on setting it can form six different crystal types. Only one, form V, gives gloss, a clean snap and the right melt. Chocolate is tempered precisely to obtain that form.
Beyond chocolate, cocoa butter is used on its own: it thins mixtures for velvet spray and for coating bonbons, it is added to ganache for firmness, and it serves as the base for fat-soluble colourings.
It is sold deodorised and natural. The first is neutral in flavour and does not interfere with added aromas; the second keeps a pronounced chocolate note.
Store at 16–18 °C away from strong smells: fat picks them up readily.